The necessity to measure and compare job levels in different organisation is known since very old times, the first important attempt we had in the history is the “TABULA DIGNITATUM” in the late Roman Empire, and similar schemas have been tried in several cases, generally without proper quantitative and statistical methods.

Starting from 1950’s, in the general framework of the organisation theory supported by the Tavistock Institute, the psychologist Elliot Jaques together with the industrial manager Wilfred Brown started a new research trying to find a proper quantitative parameter to measure the job level and to set up a criterion for equitable payment.

The research (Glacier Project, 1950) was followed by further studies on the British National Health System (Rawbottom, Billis) and other studies until the research of Ivanov (2006).

It results that job level can be measured with a proper parameter whose name is “time span of discretionality”, that this parameter can be uniformly used in any kind of organisation and eventually that it is related to the equitable payment related to the job itself.

The whole research, although started previously than "ingegneria economica" or "total cost management" were defined, has now been included in our body of knowledge. The latest studies have been submitted by Gianluca di Castri at the Conference "Methods, Models and Information Technologies for Decision Support Systems", MTISD 2008.